The present disclosure relates to a method and system for testing airtightness of a building envelope.
A building envelope is formed by physical separators between the inside and outside of a building space. The physical separators, e.g. walls, doors, and windows are typically designed to provide a certain resistance to air flow thereby helping to maintain a conditioned environment inside the building space. The building space may comprise an entire building or a part thereof, e.g. an apartment or a room.
Measuring airtightness of a building envelope can be important e.g. to minimize energy losses, assess construction quality and determine compliance with building performance standards. Typically, airtightness can be expressed as the leak flow through the building envelope for a given pressure difference between inside and outside the envelope. For example, in the Netherlands a standardized test for building airtightness (“qv10”) comprises to determine the leak flow rate through the building envelope at an induced pressure difference of 10 Pascal across the envelope. Of course the test parameters may vary, e.g. for different countries and regulations. For some tests, the flow rate value may be normalized to the surface area of the floors or to the surface area of the envelope which may comprise e.g. the ground floor, the perimeter walls and the underside of the roof or top floor ceiling.
Conventionally, airtightness is measured by a “blower door” comprising a calibrated airflow fan, a pressure measurement instrument to simultaneously measure the pressure difference induced across the building envelope, and a system for mounting the fan in a building opening such as a door or window. A typical test consists of adjusting the fan to maintain a series of indoor/outdoor pressure differences and recording the resulting average fan and indoor/outdoor pressures which can be converted to fan airflow values. However, such tests typically require large, complicated equipment and elaborate procedures.
Accordingly, it is desired to simplify and speed up the procedure for testing of building airtightness to make it economically more viable.